Elevated expression of the EZH2 gene in CALR-mutated patients with primary myelofibrosis.

Primary myelofibrosis (PMF) is one of the BCR/ABL-negative myeloproliferative neoplasms (MPNs), characterized by the diffuse fibrous hyperproliferation, bone marrow osteosclerosis, extramedullary hematopoiesis, and marked splenomegaly. The patients with PMF have an insidious onset, a long duration of clinical course, and the deteriorated quality of life. It has been reported that the CALR gene 9 exon mutations were detected in 25-30% PMF patients, particularly as high as 80% in the JAK2/MPL-negative ones. As the second most common mutation in BCR/ABL-negative MPNs, CALR mutation has been included in the latest World Health Organization (WHO) classification criteria as one of the main diagnostic criteria for both essential thrombocythemia (ET) and PMF. Moreover, the CALR mutations indicated a favorable prognosis, which the mechanism is still under investigation. It was demonstrated that a characterized high expression of EZH2 and SUZ12 in CALR-mutated patients. Taking EZH2 as the research entry point, we initially discussed the mechanism that the CALR-positive patients with PMF exhibited a better prognosis in the current study.